The present application claims priority rights of and is based on subject matter described in Japanese patent applications respectively filed in the Japanese Patent Office as listed below, the entire contents of which are hereby incorporated by reference:
1. JPAP10-353223 filed on Dec. 11, 1998,
2. JPAP11-029210 filed on Feb. 5, 1999, and
3. JPAP11-269096 filed on Sep. 22, 1999.
1. Field of the Invention
The present invention generally relates to a method and apparatus, and more particularly to a method and apparatus for image processing which is capable of performing a density adjustment with respect to an output data signal for optical writing in which gray-scale is performed by at least one of plural methods including a manipulation of a plurality of dots, a density adjustment on a single dot, and a size adjustment on a single dot.
2. Discussion of the Background
In an image forming apparatus, density of a pixel is generally adjusted with a manipulation of a plurality of dots arranged in a form of matrix, a single-dot-based density adjustment, or a single-dot-based size adjustment. Various image density adjusting methods using multiple-value dithering have been developed. One example is Japanese Laid-Open Patent Application No. 3-80768 (1991). In this example, density adjustment with dithering is first performed with respect to multiple-value input image data. Then, multiple-value dithering is performed on the adjusted input multiple-value image data. Finally, density correction according to a printer output characteristic is performed on the resultant multiple-value dither data. With this method, density adjustment on multiple-value input image data can suitably be made to a variety of printer characteristics.
However, the above described method cannot reproduce an optimal dot in-accordance with conditions of neighboring dot positions. That is, the above method will make an inferior reproduction with respect particularly to a highlight or line portion. Further, it performs the multiple-value dithering using a single gamma correction table. Therefore, the above method cannot produce an output data signal for image writing in which gray-scale is performed for various different density adjustment operations based on, for example, a manipulation of a plurality of dots, a density adjustment on a single dot, and a size adjustment on a single dot.
Accordingly, an object of the present invention is to provide a novel image forming apparatus which can optimally reproduce a dot with superior fidelity to produce an output data signal for image writing in which gray-scale is performed based on, for example, a manipulation of a plurality of dots, a density adjustment on a single dot, and a size adjustment on a single dot.
To achieve this and other objects, the present invention provides a novel image forming apparatus which makes gray-scale by performing at least one of operation including a manipulation of a plurality of dots arranged in a form of matrix, a single-dot-based density adjustment, or a single-dot-based size adjustment, includes a dot status detector and a density adjuster. The dot status detector detects an occurrence in which a dot exists at a focus dot position and no dot exists at positions immediately adjacent to the focus dot position in the main scanning direction. The density adjuster adjusts a writing level of the dot at the focus dot position so as to make the gray-scale smooth when the dot status detector detects the occurrence.
The above mentioned image forming apparatus may further include a dot phase adjuster for slightly displacing a position of dot right from a center of dot when the dot status detector detects the occurrence and left from a center of dot during a time other than when the dot status detector detects the occurrence.
The present invention also provides an image forming apparatus which generates gray-scale data by perform at least one operation including a manipulation of a plurality of dots arranged in a form of matrix, a single-dot-based density adjustment, or a single-dot-based size adjustment in accordance with commands sent from an external host system, includes a writing level adjuster and a gray-scale processor. The writing level adjuster adjusts a writing level in accordance with at least one of a density and a size of dots at positions adjacent to a focus dot position. The gray-scale processor generates gray-scale data of a line relative to input data when the commands relate to a line forming operation and of an image relative to input data when the commands relate to an image forming operation.
The gray-scale processor may convert input data with a value of a lowest level among predetermined multiple levels when the input data has a value other than 0.
The above-mentioned image forming apparatus may further includes a surrounding data detector detecting data of dots at positions immediately adjacent to a focus dot position and a writing value changer changing writing values of the multiple levels in accordance with data detected by the surrounding data detector.
The gray-scale processor may perform a dispersive gray-scale operation for generating gray-scale data of a line relative to input data and an intensive gray-scale operation for generating gray-scale data of an image relative to input data.
The present invention also provides a method of image forming which makes gray-scale by performing at least one of operations including a manipulation of a plurality of dots arranged in a form of matrix, a single-dot-based density adjustment, or a single-dot-based size adjustment, includes the steps of detecting an occurrence in which a dot exists at a focus dot position and no dot exists at positions immediately adjacent to the focus dot position in the main scanning direction and adjusting a writing level of the dot at the focus dot position so as to make the gray-scale smooth when the detecting step detects tho occurrence.
Other objects, features, and advantages of the present invention will become apparent from the following detailed description when read in conjunction with the accompanying drawings.